Thermal Fusion of Lithium‐Philic Fluorinated Bi ₂ O ₂ CO ₃ to Derive Heterogeneous SEI and Dendrite‐Free Li Plating for the First Ah‐Level Fluoride Conversion Pouch Cells

ABSTRACT The artificial solid electrolyte interface (ASEI) is regarded as a simple yet highly effective approach to enhance both the electrochemical and mechanical stability of the anode‐electrolyte interface. In this study, we propose the thermal fusion of fluorine‐incorporated Bi ₂ O ₂ CO ₃ (F‐BOC) with lithium metal to construct a lithium‐philic ASEI functioning as an interface rectifier to regulate lithium‐ion deposition and stripping. The introduction of fluorine promotes the Li adsorption capability of F‐BOC, and the formation of an isotropic and compact structure that blocks TFSI ⁻ anions outside the ASEI layer. Under sustained electrochemical operation, a heterogeneous LiF‐Li ₂ CO ₃ conductive nanodomain region is generated from F‐BOC, facilitating the lithium‐ion transport across the LiF‐Li ₂ CO ₃ interface, which effectively suppresses lithium dendrite growth and electrode expansion. The F‐BOC‐modified LiNi _0.8 Co _0.1 Mn _0.1 O ₂ full cells demonstrate excellent cycling stability, with a high capacity retention of 85.88% over 600 cycles at 1 C and a capacity retention of 90.3% over 120 cycles under high active material loading 20 mg cm ⁻² . Moreover, the modified thin lithium anodes (60 µm in thickness) achieve stable cycling in 15‐layer pouch cells based on high‐capacity FeF ₃ , delivering a capacity of nearly 1 Ah, which is the highest level for fluoride conversion reaction batteries.